Heated intake component for gas turbine engines



April 22, i952 w- BOYD 2,594,118

HEATED INTAKE COMPONENT FOR GAS TURBINE ENGINES Filed April 7, 1949 5 Sheets-Sheet 2 INVENTOR WINNETT BOYD.

ATTORNEY April 22, 1952 W, BOYD 2,594,118

'HEATED INTAKE COMPONENT FOR GAS TURBINE ENGINES Filed April 7, 1949 3 SheeVcs--Sheexl 3 mvzNToR WINNETT bBox/D.

ATTORNEY Patented Apr. 22, 1952 HEATED INTAKE COMPONENT FOB GAS TURBINE ENGINES I Winnett Boyd, Bobcaygeon, Ontario, Canada, as-

signor Yto A. V. Roe Canada Limited, Malton, Ontario, Canada, a corporation Application April 7, 1948, Serial No. l86,057

l This invention relates to means for preventing the formation of ice on aircraft surfaces, and more particularly to means for preventing ice Vformation of the air intake components of air compressors which are associated with aircraft gas turbine engines.

The application of gas turbine engines to aircraft has introduced a serious icing problem in view of the particular vulnerability of gas turbine engines to ice formation. The formation of ice on such intake components as the intake fairing, the nose bullet, and the struts supporting the front bearing, causes serious obstruction to the ow of air passing into the compressor and considerable damage may result from pieces of ice s claims. (o1.A aie-,434.) f

2 appreciable heating of the chargel of air entering the compressor and to provide a ready means for the application of heat where it is most required. L

All ofthe foregoing and still further objects and advantages of the invention will. become apparent from a study of the following specication, taken in conjunction with the accombreaking loose and being carried by the air stream, into the rotating parts. These hazards canbeavoided either by the introduction of a fluidv such as alcohol to lower the freezing point of the `mixture coming into contact withthe components, or by the application of heat to raise the surface temperature of the inlet parts above the freezing point of water. The chief objections to the former method lie in the complications involved in the fluid supply system suflcient fluid can be carried to enable the system to function intermittently and the system therefore cannot be turned on until icing conditions have been detected, by which time some v ice will have alreadly formed. The secondr method, involving application of heat, can be employed in a number of ways but care must be taken to avoid an excessive heating of the bulk of the air passing into the compressor, since this would materially impair the compressor performance, and furthermore, it is necessary to avoid complicating the heating installation as Lfar as possible.

Means have been devised heretofore for utilizv ing hot gases to prevent the formation of ice on the components of aircraft having internal combustion engines, but such means are not adapted wasted to the atmosphere in the normal course 'of operation of the engine, rather than electrical or other forms of heat which require to be generated specifically for anti-icing purposes. Another object of this invention is to avoidand the fact that for reasons of weight, onlypanying drawings wherein like characters of reference indicate corresponding parts throughout the several views and wherein: I

Fig. l is a front elevation, partly broken away, of the air intake of the air compressor of a gas turbine constructed in accordance with this invention;

Fig. 2 is an elevation, partly in section on the line II-II of Fig. 1; j

Fig. 3 is a cross-section of a strut on the line III-III of Fig. 2; and Y v Fig; 41 isi an elevation partly in sectionto an enlarged scale showing the nose bullet and cap assembly; v

In the compressor assemblythe first stage of rotor blades are mounted within a stator casing 6. Immediately forward of the rotor blades are the inlet guide vanes 'I. The; rotor shaftfB having a front bearing 9 is linked by gearing I0 to an auxiliary drive I I and housed in an-intake structure I2 which is composed, of` an outer portion I2, an inner portion I2band interconnecting struts I3, the whole being fastened to the outer stator casingl 6 at the'flange 6a. Struts I3 are arranged in cruiciform and may vary from 3 in number upward to 8 in number or :even more. The struts I3 each have a hollow leading edge member I4 secured thereto. The leading edge members I4 form enclosed conduits; for the flow of heated air.

On the front of the casing I2 are mounted the engine starter I5 and a detachable central or inner intake fairing or nose bullet I5. The nose bullet I5 is constructed with a double skin constituted by an inner or bale wall I6@ and Yan outer or duct wall Iiib spaced by the webbing IBG. The circulation passage I'I provided'between the bale wall and the duct wall is in communication with the conduits I4 formed in the leading edges of struts I3, so that a heating medium may be carried into the passage I1 from the conduits I4. The nose bullet is held in place by a cap I8 which overlaps the duct wall [6b and which is bolted to a bracket I9 mounted onA the front of the starter I5. "The outer edge of the cap I3 is spaced from the duct wall IGbof the .nose bullet so as to provide an annular outlet 2n between the said capvand the duct wall. The

cap I8 has a shoulder I8a which engages van annular flange 2| secured to the baffle wall ida of the nose bullet IS, thereby sealing offk the passage I1 from communication with the interior of the nose bullet I6. By tightening the cap I8 against the, flange 2|, the baflle wall I5a and the duct walls I6b of the nose bullet are caused to bear against the O-ring type seal 22 and the cone rseat 23, respectively, provided on the face of the intake structure I2. Whenvaccess to the starter is required, the nose bullet Iii may be readily removed by unscrewing the cap I8 Vand withdrawing the nose bullet from contact with the seal 22 and the seat 23.

It may be noted that if the starter employed is of aytype requiring an exhaust outlet, the double wall of the nose bullet I6 may be used for this purpose. A duct 24, which will be required only for this type of starter, is provided to con- "f'= 'nect thestarter to the circulation passage I1.

Spaced from the nose bullet IB is an annular outer intake fairing 25 extending forwardly from an annular bulkhead which is coaxial with the compressor and denes with the central or inner intake fairing or nose bullet I6 an annular duct through which air enters the compressor. The

1 annular fairing 25 includes a hollow annular fairing shell 25b provided by a distal or peripheral Cowling wall and an intake Wall, which converge towards each other and curve and blend into each other at the front. Within the annular fairing shell 25b is positioned a hollow annular baffle shell 25 having bafiie walls regularly spaced by f webbing 25 from the opposed walls of the fairing shell, the space between the fairing shell 25b and the baille shell 25a providing a continuous circulation passage 26.

` Adistribution chamber 21, bounded by the fairing 25and the bulkhead 28, is connected to the conduits I4 in the leading edges of the struts I3.

' A conduit or duct 29, connected to the bulkhead rso as to face toward the compressor.

In the operation of the anti-icing system, suitable hot air is introduced through duct 29 to the chamber 21. The various arrangements for supplying the hot air are not important to this invention, and have not been illustrated. Some of the hot air which is introduced flows from the chamber 21 through the circulationV passage 2B within the fairing 25 and escapes from the annular slot 30. The slot 30 is so situated that the air escapingvfrom it must pass through the circulation passage 26 and heat from within the outer surface of the fairing shell 25h. A portion ofthe intake wall of the fairing shell 25b is bent outwardly adjacent to the slot 30 to provide a dflectr 3I for the issuing air. In escaping from.`

the slot 30, the air consequently is directed toward the compressor and clings closely to the intake wall as it passes into the compressor with 'the main air stream through the intake duct formed by the annular fairing 25 and the nosebullet I5.

Another part of the hot air in the chamber 21 flows through the leading edges I4 of the struts I3 and thence into the circulation passage I1 under the skin of the central fairing or nose bullet. This air will eventually escape from the slot 2t and be directed toward the compressor by the edge portion of the cap I8which acts as a deflector for the issuing air, which will then flow along the outer surface of the nose bullet i6, clinging closely to its surface, as it is carried along by the main flow into the compressor.

in the circulation of hot air under the shell of the outer intake fairing, the struts, and the nose bullet, the transfer of heat is dependent not only upon the local temperature of the hot air, but also on its local velocity; by a choice of the size of conduits and circulation passages, the velocity of the flow of the hot air can be arranged to suit the transfer of heat required at any particular point. By this means distribution of heat can be arranged at will to meet the distribution of possible ice formation which is in generalmost serious on the tip ofthe nose bullet I5 and the forward face of the fairing 25. Furthermore in escaping through the slots 20 and 3d the exhaust air aids in the prevention of ice formation by film heating. In this connection, attention is directed to the analogy of lm cooling which operates effectively over the llame tubes of gas turbine combustion chambers under conditions of much greater turbulence than exist in the air intake.

The volume of hot air escaping from the slots 2t and 30 will be very small in proportion to the volume of the air fiowing into the compressor and will not materialh7 raise the temperature thereof. Furthermore, it will be of no serious consequence if a certain amount of leakage occurs at the seal 22 and seat 23 or anywhere else in the system.

It is to be understood that the form ofthe invention, herewith shown and described, is to be taken as a preferred example of the same, and that various changes in the shape, size and arrangement of the parts may be resorted to, without departing from the spirit of the invention or the scope of the claims.

What I claim as my invention is:

l. l-Ieated intake components-'for a gas turbine engine Vcomprising an annular fairing including a hollow annular fairing shell provided by a cowling wall and an intake wall which converge to wards each other and curve and blend into each other at the front, a hollow annular baille shell disposed within the fairing shell and having baflle walls regularly spaced from the opposed cowling and intake walls of the fairing shell, an annular distribution chamber within the fairing shell and adjacent the bale shell, the space between the bafiie walls and the opposed cowling and intake walls providing a continuous circulation passage communicating with the distribution chamber, a central fairing disposed substantially coaxially with respect to the annular fairing shell and spaced from the intake wall, the central fairing having a double wall comprising a duct wall and another baiile wall spaced from the duct wall, the duct wall and the other baille wall providing another circulation passage within the double wall of the central fairing, the duct wall of the central fairing defining with the intake wall of the annular fairing an annular intake duct by which air is guided into the engine, a source of hot gases, a conduit for introducing the hot gases into the distribution chamber, conduits for conveying the hot gases from the distribution chamber to the said other circulation passage, and continuous annular outlets in the intake wall and in the duct wall for discharging the hot gases into the intake duct.

2mg-coglie 2. Heated'inta'kecomponents for a gas turb-ine and an intakewallldeliningtan,V intake duct and exposed tothe main airstream entering the engine,and a hollow baiile'shlll disposed withinthe f.fairing-shellA and havingbaiiie' wallsjreg'ularly "spaced from the-opposed cowling `and intakewalls of the fairing shell, webbing between the fairing i shell and the baiile shell and supporting the baille shell within the fairing shell, an annular distribution chamber within the fairing shell and adjacent the baille shell, the space between the baille walls and the opposed cowling and intake walls providing a continuous circulation passage communicating with the distribution chamber, a source of hot gases, a conduit for introducing the hot gases into the distribution chamber, and la continuous annular outlet in the intake wall at the forward end thereof for discharging the hot gases into the intake duct.

3. Heated intake components for a gas turbine engine comprising an annular bulkhead at the front of the engine, an annular fairing including a hollow annular fairing shell provided by a cowling wall extending forwardly from the outer diameter of the bulkhead and an intake wall extending forwardly from the inner diameter of the bulkhead, which walls converge towards each other and curve and blend into each other at the front, a hollow annular baille shell disposed within the fairing shell and having baille walls regularly spaced from the opposed cowling and intake walls of the fairing shell, the baille walls terminating rearwardly in a plane spaced from the bulkhead, webbing between the fairing shell and baille shell and supporting the baille shell. within the fairing shell, the space between fthe baille shell and the bulkhead providing a distribution chamber, the space between the baille walls and the opposed cowling and intake walls providing a continuous circulation passage com-- municating with the distribution chamber, a source of het gases, a conduit for introducing the hot gases through the bulkhead into the distribution chamber, and a continuous annular outlet in the intake wall at a point remote from the annular bulkhead for discharging the hot gases.

4. Heated intake components for a gas turbine engine comprising an annular bulkhead atlthe front of the engine, an annular fairing including a hollow annular fairing shell provided by a cowlingwall extending forwardly from the outer diameter of the bulkhead and an intake wall extending forwardly from the inner diameter of the bulkhead, which walls converge towards each other and curve and blend into each othei` at the front, a hollow annular baiile shell disposed within the fairing shell and having baille walls regularly spaced from the opposed cowling and intake walls of the fairing shell, the baffle walls terminating rearwardly in a plane spaced from the bulkhead, webbing between the fairing shell and baille shell and supporting the baffle shell within the fairing shell, the space between the baille shell and the bulkhead providing a distribu tion chamber, the space between the baille walls and theopposed cowling and intake walls providing a continuous circulation passage communicating with the distribution chamber, a central fairing disposed substantially coaxially with respect to the annular fairing shell and spaced from the intake wall, the central fairing having a? double'V wall colfnprisingA aiductfwallr-.and if another" baffle 'w'alli' spacdifromf thelduc wall.

the duct wall fand Ithe` other` bafefwall; providing anotherecirculation passage within the double wall of the central fairing, the duct wall of the central fairingfd'eflningiwiththe intake wall of theannulariairing an annularintake duct by f which air is guided into" the,eriginepefysourceof hot gases, a conduit for introducing the""hot gases through the bulkhead into the distribution chamber, hollow struts extending radially from the intake wall to the duct wall and connecting the distribution chamber with the said other circulation passage, and continuous annular outlets in the intake wall and in the duct wall at locations remote from the engine for discharging the hot gases into the intake duct.

5. Heated intake components for a gas turbine engine comprising an annular fairing extending forwardly of the engine and dened. by a double wall, the double wall including spaced-apart opposing walls defining a circulation passage between the walls, a central fairing disposed substantially coaxially with respect to the annular fairing and spaced from the double wall, the sides of the central fairing being defined by a removable double wall including spaced-apart opposing walls defining another circulation passage between the walls of the central fairing, the central fairing having a nose cap removably secured to the engine, the cap having an annular shoulder engaging the front edge of one wall of the central fairing to secure the double wall of the central fairing to the engine, the nose cap being spaced from the other wall of the central fairing and providing a continuous annular outlet from the said other circulation passage, and conduits for introducing the hot gases into the rst-mentioned circulation passage and for conveying the hot gases to the said other circulation passage, at least part of the hot gases being discharged from the annular outlet. i

6. Heated intake components for a gas turbine engine comprising an annular fairing extending forwardly of the engine and dened by a double wall, the double wall comprising spacedapart opposing walls dening a circulation passage between the walls, a central fairing disposed substantially coaxially with respect to the annular fairing and spaced from the double wall to denne with the double wall an annular intake duct by which air is guided into the engine, the central fairing being defined by a removable double wall comprising a duct wall and a baille wall spaced from the duct wall, the duct wall and the baille wall providing another circulation passage within the double wall of the central fairing, the central fairing, having a nose cap removably secured to the engine, the cap having an annular shoulder engaging the front edge of the baille wall of the central fairing to secure the double wall of the central fairing to the engine, the nose cap also having a substantially circular edge spaced from the duct wall of the central fairing and providing a continuous annular outlet from the said other circulation passage, the circular edge of the nose cap extending toward the engine beyond the front edge of the duct wall to provide a deiiector, a source of hot gases, and conduits for introducing the hot gases into the first-mentioned circulation pasage and for conveying the hot gases to the said other circulation passage, at least part of the hot gases being discharged from the annular 7 outlet and deected by' the deflector over the surface of the duct wall between the air entering the compressor andthe duct Wall.

WINNETT BOYD.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Number Name Date Keller May 4, 1943 Sammons Sept. 20, 1949 FOREIGN PATENTS Country Date Sweden July 29, 1941 France -1 Apr. 8, 1941 

